Business and Summary of Significant Accounting Policies - Changes In the Carrying Amount of Goodwill (Details) - USD ($)	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Accounting Policies [Abstract]
Impairment of goodwill	$ 0	$ 0	$ 0
Goodwill [Roll Forward]
Goodwill, beginning of period, gross		1,769,400,000	1,710,300,000
Less: accumulated impairment losses, beginning of the year		(149,200,000)	$ (149,200,000)
Additions arising from acquisitions during the year	866,900,000	0
Effect of foreign currency translation, measurement period adjustments, and other (1)	(36,300,000)	59,100,000
Goodwill, end of period, net	$ 2,450,800,000	$ 1,620,200,000